(a) Field of the Invention
The present invention relates to a variable intake system for a vehicle, and more particularly, to a variable intake system with a vacuum chamber inside an intake manifold.
(b) Description of the Related Art
A variable intake system adjusts the runner length of an intake manifold. The variable intake system includes a throttle body, a surge tank communicating with the throttle body, an intake manifold having a plurality of runners to which air is dispensed from the surge tank, an opening/closing unit for adjusting the runner length, an actuator that activates the opening/closing unit, and a vacuum chamber for driving the actuator.
Vacuum chambers have been developed as an independent engine component. The vacuum chamber can be designed without shape or size limitations to have sufficient volume. Furthermore, the mounting position of the vacuum chamber can be freely selected.
The mounting position of the vacuum chamber is determined by the layout of the engine and vehicle. The vacuum chamber must be sufficient in size and the connection tube that connects the vacuum chamber must be simple in design.
Further, an effort to manufacture the variable intake system using plastic has continued to reduce the weight of the engine. However, the vacuum chamber requires many components such as a mounting bracket, a bracket coupling member, an actuator, and a vacuum hose connecting the actuator to the vacuum chamber. Therefore, the manufacturing cost increases and the space taken by the vacuum chamber increases.
Also, experiments show that noise increases when the variable intake system is formed of plastic. Particularly, this noise is primarily generated by the increase of a flow ratio when air passes through the throttle body, and is secondarily generated when the air passes through the runners of the intake manifold.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.